Here are the answers to your questions:
1. If I retake the exam, does the same questions appear or it takes a mix of unanswered and incorrectly answered questions?
Exam 1 - Exam 7 all have 200 pre-assigned questions. So if you take Exam 1 three times, then you will see the same 200 questions three times. Just in a different order.
2. The 8th exam on ITTO is a full 4 hrs exam? Do you recommend taking it or just do it separately?
Memorizing ITTOs is less and less important to pass the exam. But if you want to test yourself on ITTOs then Exam 8 is a good way to do that.
I would also like to recommend the following :
1. If you have not yet seen this, please watch the simulator tutorial
traffic.libsyn.com/pmpodcast/lms_using_t...mulator_tutorial.mp4
2. And then take a look at the other simulator tutorials by visitng
www.project-management-prepcast.com/tutorials
and then click on "Exam Simulator Tutorials". In particular watch "how to start a timed or learning Quiz"